From Papillary Muscle Rupture to Left Atrial Pseudoaneurysm: A Rare Sequential Complication After Acute Myocardial Infarction and Mitral Valve Replacement

Papillary muscle rupture is a rare but life-threatening mechanical complication of acute myocardial infarction, resulting in acute severe mitral regurgitation and cardiogenic shock. Emergency surgical intervention is essential for survival. Left atrial intramural hematoma and subsequent pseudoaneurysm formation are exceptionally rare complications of mitral valve surgery, with no established management strategy. We report the case of a 77-year-old man presenting with acute severe mitral regurgitation secondary to complete rupture of the posteromedial papillary muscle following an inferior myocardial infarction. He underwent emergency mitral valve replacement with a favorable postoperative course. Routine postoperative imaging unexpectedly revealed a left atrial wall hematoma, which evolved into a stable left atrial pseudoaneurysm on follow-up cardiac computed tomography. Given the absence of symptoms or lesion progression, conservative management with imaging surveillance was adopted. This case highlights the value of multimodality imaging in the diagnosis and follow-up of rare postoperative complications and supports a conservative approach in carefully selected clinically stable patients.